There are those of us in Britain who think it’s crazy that people still drink hot drinks on a hot summer’s day. But anyone who’s lived in a hot climate like India, Australia or anywhere in Africa will tell you that there’s method to the madness. Hot beverages have counterintuitive cooling powers and there’s research to prove it. Anthony Bain, a PhD candidate at the Centre for Heart, Lung and Vascular Health at the University of British Columbia has investigated the physiological mechanics of the phenomenon to shed some light on why drinking hot drinks in hot weather actually works to cool us down.
We all know that when we’re hot, the body’s natural way to cool us down is through sweating. Scientifically, the important bit is having sweat evaporate from our bodies. When you delve into the science behind our physical reaction, you discover that our bodies sense changes in tissue temperature through a network of thermosensors located in our skin and in more central parts of our body which send signals to our brain (more specifically, the hypothalamus) which then triggers the sweat reaction we all experience in hot weather. When we drink something hot, the thermosensors in our stomach become overactive and send strong signals to the hypothalamus indicating that we’re hot and need to cool down. The hypothalamus reacts by causing an over-compensatory sweating response. When the sweat evaporates from our skin, the heat energy we lose due to evaporation exceeds the heat energy gained by drinking the hot drink. So it’s because our body overreacted to the hot drink that we end up feeling cooler as a result.
So while it might seem crazy to drink a hot coffee on a hot day, it’s actually a great way to help cool us down. And believe it or not, plenty of savvy Brits don’t give up on that daily caffeine habit just because it’s sunny and sweltering. And 65% of takeaway coffee consumers partake in that daily habit in the morning.
Why your weird friends are drinking hot coffee in the summer by Melissa Dahl (Science of Us, NY Magazine).